The covering materials here considered generally come in sections which must be pieced together in abutting relationship when being nailed, pasted or otherwise applied to the surface to be lined thereby. At least some of these sections, such as those coming to adjoin the edges of that surface, must be precisely cut to size in order to conform to the area that is to be covered. In many instances, especially with rigid workpieces such as veneers, glass panes, plastic sheets or metal plates, the sizing must be done in advance on the basis of measurements taken at the site. The handling of measuring tapes used for this purpose often requires the assistance of a second person; if a tape is too short to extend over the length or height of a wall, it must be shifted along the surface after a reference point has been marked thereon. These procedures are awkward and tend to give rise to errors which must be corrected by a trimming of workpieces cut too large or a replacement of others that turned out undersized.